Electromagnetic shielding comprises the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. Shielding is typically applied to enclosures to isolate electrical devices from the outside world, and to cables to isolate wires from the environment through which a cable runs. Electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as RF shielding. The shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. A conductive enclosure used to block electrostatic fields is also known as a Faraday cage. The amount of reduction depends upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in the shield to an incident electromagnetic field.
Radio frequency shielding has been traditionally performed using metal structures such as cans. The structure is usually either one piece so that the walls and the top part of the structure such as a roof are made of the same metal sheet, or a two piece system, where walls, establish a frame of the structure, and one piece as the top part which can be disconnected from the structure, for example a common soup can structure.